A computer numeric controlled machining system, hereinafter referred to as a CNC machining system, comprises a movable toolhead support assembly which traverses left to right along a horizontal beam or gantry in the x direction. Mounted to the movable toolhead support assembly is a toolhead, adapted to be displaced in a vertical or z direction on a set of rails, and generally fitted with an electric routing spindle. A worktable is situated beneath the toolhead, the surface of which is situated parallel to the x-y plane. Moving the gantry to which the tool carrier is mounted, or on some machines, moving the worktable itself, effects movement in the y direction. On certain machines, instead of a toolhead being mounted to the toolhead support assembly, a vertical column, displaceable in the z-axis direction, may be affixed thereto. A toolhead, comprising a rotating c-axis assembly, and a rotating a-axis assembly, is mounted thereon. All of the axes, along with the toolhead, are calibrated to have a specific angular and linear displacement with respect to a predetermined reference point.
A considerable amount of time and skilled labor are required to achieve an acceptable state of calibration for the machine as described. The state of calibration must be maintained in order to achieve satisfactory performance from the machine. Over a period of time, in the course of normal machine use, or in the event of an accidental collision of the tool head, it is possible for one or more of the various components to move out of alignment. When an event such as this occurs, lengthy calibration procedures must be performed in order to bring the machine back into an acceptable state of calibration. This not only consumes skilled resources, but also results in the loss of the use of the machine. The present invention provides a solution to this problem by providing for automatic calibration compensation by means of software-controlled modification of the servo positioning loop data.